drbdsetup {
device
} {disk} {
lower_dev
} {
meta_data_dev
} {
meta_data_index
} [-d{size}] [-e{err_handler}] [-f{fencing_policy}] [-b]
drbdsetup {
device
} {net} [
af:
] {
local_addr
} [
:port
] [
af:
] {
remote_addr
} [
:port
] {
protocol
} [-c{time}] [-i{time}] [-t{val}] [-S{size}] [-k{count}] [-e{max_epoch_size}] [-b{max_buffers}] [-m] [-a{hash_alg}] [-x{shared_secret}] [-A{asb-0p-policy}] [-B{asb-1p-policy}] [-C{asb-2p-policy}] [-D] [-R{role-resync-conflict-policy}] [-p{ping_timeout}] [-u{val}] [-d{hash_alg}] [-o]
drbdsetup {
device
} {syncer} [-a{dev_minor}] [-r{rate}] [-e{extents}] [-v{hash-alg}] [-c{cpu-mask}]
drbdsetup {
device
} {disconnect}
drbdsetup {
device
} {detach}
drbdsetup {
device
} {down}
drbdsetup {
device
} {primary} [-o]
drbdsetup {
device
} {secondary}
drbdsetup {
device
} {verify}
drbdsetup {
device
} {invalidate}
drbdsetup {
device
} {invalidate-remote}
drbdsetup {
device
} {wait-connect} [-t{wfc_timeout}] [-d{degr_wfc_timeout}] [-w]
drbdsetup {
device
} {wait-sync} [-t{wfc_timeout}] [-d{degr_wfc_timeout}] [-w]
drbdsetup {
device
} {state}
drbdsetup {
device
} {cstate}
drbdsetup {
device
} {dstate}
drbdsetup {
device
} {status}
drbdsetup {
device
} {resize} [-d{size}]
drbdsetup {
device
} {pause-sync}
drbdsetup {
device
} {resume-sync}
drbdsetup {
device
} {outdate}
drbdsetup {
device
} {show-gi}
drbdsetup {
device
} {get-gi}
drbdsetup {
device
} {show}
drbdsetup {
device
} {suspend-io}
drbdsetup {
device
} {resume-io}
drbdsetup {
device
} {events} [-u] [-a]
drbdsetup {
device
} {new-current-uuid} [-c]
drbdsetup is used to associate DRBD devices with their backing block devices, to set up DRBD device pairs to mirror their backing block devices, and to inspect the configuration of running DRBD devices.
drbdsetup is a low level tool of the DRBD program suite. It is used by the data disk and drbd scripts to communicate with the device driver.
Each drbdsetup sub-command might require arguments and bring its own set of options. All values have default units which might be overruled by K, M or G. These units are defined in the usual way (e.g. K = 2^10 = 1024).
All drbdsetup sub-commands accept these two options
--create-deviceIn case the specified DRBD device (minor number) does not exist yet, create it implicitly.
--set-defaults When --set-defaults is given on the
command line, all options of the invoked sub-command that
are not explicitly set are reset to their default values.
Associates device with
lower_device to store its data blocks on.
The -d (or --disk-size) should
only be used if you wish not to use as much as possible from the
backing block devices.
If you do not use -d, the device
is only ready for use as soon as it was connected to its peer once.
(See the net command.)
-d,
--disk-size size You can override DRBD's size determination method with this
option. If you need to use the device before it was ever
connected to its peer, use this option to pass the
size of the DRBD device to the
driver. Default unit is KB (1 KB = 1024 bytes).
-e,
--on-io-error err_handler If the driver of the lower_device
reports an error to DRBD, DRBD will either pass the error
to the upper layers of the operating system, call a helper
program, or detach the device from its backing storage and
perform all further IO by requesting it from the peer. The
valid err_handlers are:
pass_on, call-local-io-error
and detach.
-f,
--fencing fencing_policy Under fencing we understand preventative
measures to avoid situations where both nodes are primary
and disconnected (AKA split brain).
Valid fencing policies are:
dont-care
This is the default policy. No fencing actions are undertaken.
resource-only
If a node becomes a disconnected primary. it tries to outdate the peer's disk. This is done by calling the outdate-peer handler. The handler is supposed to reach the other node over alternative communication paths and call 'drbdadm outdate res' there.
resource-and-stonith
If a node becomes a disconnected primary, it freezes all
its IO operations and calls its outdate-peer handler. The
outdate-peer handler is supposed to reach the peer over
alternative communication paths and call 'drbdadm outdate
res' there. In case it cannot reach the peer, it should
stonith the peer. IO is resumed as soon as the situation
is resolved. In case your handler fails, you can resume
IO with the resume-io command.
-b,
--use-bmbvIn case the backing storage's driver has a merge_bvec_fn() function, DRBD has to pretend that it can only process IO requests in units not lager than 4kByte. (At time of writing the only known drivers which have such a function are: md (software raid driver), dm (device mapper - LVM) and DRBD itself)
To get best performance out of DRBD on top of software raid (or any other driver with a merge_bvec_fn() function) you might enable this function, if you know for sure that the merge_bvec_fn() function will deliver the same results on all nodes of your cluster. I.e. the physical disks of the software raid are exactly of the same type. USE THIS OPTION ONLY IF YOU KNOW WHAT YOU ARE DOING.
-a, --no-disk-barrier, -i, --no-disk-flushes, -D, --no-disk-drainDRBD has four implementations to express write-after-write dependencies to its backing storage device. DRBD will use the first method that is supported by the backing storage device and that is not disabled by the user.
When selecting the method you should not only base your decision on the measurable performance. In case your backing storage device has a volatile write cache (plain disks, RAID of plain disks) you should use one of the first two. In case your backing storage device has battery-backed write cache you may go with option 3 or 4. Option 4 will deliver the best performance such devices.
Unfortunately device mapper (LVM) does not support barriers.
The letter after "wo:" in /proc/drbd indicates with method is currently in use for a device: b, f, d, n. The implementations:
The first requirs that the driver of the
backing storage device support barriers (called 'tagged command queuing' in
SCSI and 'native command queuing' in SATA speak). The use of this
method can be disabled by the we --no-disk-barrier option.
The second requires that the backing device support disk flushes (called
'force unit access' in the drive vendors speak). The use of this method
can be disabled using the --no-disk-flushes option.
The third method is simply to let write requests drain before
write requests of a new reordering domain are issued. That was the
only implementation before 8.0.9. You can prevent to use of this
method by using the --no-disk-drain option.
The fourth method is to not express write-after-write dependencies to the backing store at all.
-m,
--no-md-flushes Disables the use of disk flushes and barrier BIOs when
accessing the meta data device. See the notes
on --no-disk-flushes.
-s,
--max-bio-bvecsIn some special circumstances the device mapper stack manages to pass BIOs to DRBD that violate the constraints that are set forth by DRBD's merge_bvec() function and which have more than one bvec. A known example is: phys-disk -> DRBD -> LVM -> Xen -> missaligned partition (63) -> DomU FS. Then you might see "bio would need to, but cannot, be split:" in the Dom0's kernel log.
The best workaround is to proper align the partition within the VM (E.g. start it at sector 1024). Costs 480 KiByte of storage. Unfortunately the default of most Linux partitioning tools is to start the first partition at an odd number (63). Therefore most distribution's install helpers for virtual linux machines will end up with missaligned partitions. The second best workaround is to limit DRBD's max bvecs per BIO (= max-bio-bvecs) to 1. Might cost performance.
The default value of max-bio-bvecs is 0, which means that
there is no user imposed limitation.
Sets up the device to listen on
af:local_addr:port for incoming connections
and to try to connect to af:remote_addr:port.
If port is omitted, 7788 is used as default.
If af is omitted ipv4 gets
used. Other supported address families are ipv6 and
sci for Dolphin Interconnect Solutions' "super sockets".
On the TCP/IP link the specified protocol
is used. Valid protocol specifiers are A, B, and C.
Protocol A: write IO is reported as completed, if it has reached local disk and local TCP send buffer.
Protocol B: write IO is reported as completed, if it has reached local disk and remote buffer cache.
Protocol C: write IO is reported as completed, if it has reached both local and remote disk.
-c,
--connect-int timeIn case it is not possible to connect to the remote DRBD device immediately, DRBD keeps on trying to connect. With this option you can set the time between two tries. The default value is 10 seconds, the unit is 1 second.
-i,
--ping-int time If the TCP/IP connection linking a DRBD device pair is idle
for more than time seconds, DRBD
will generate a keep-alive packet to check if its partner is
still alive. The default value is 10 seconds, the unit is 1 second.
-t,
--timeout val If the partner node fails to send an expected response packet
within val
10ths of a second, the partner node
is considered dead and therefore the TCP/IP connection is
abandoned. The default value is 60 (= 6 seconds).
-S,
--sndbuf-size size The socket send buffer is used to store packets sent to the
secondary node, which are not yet acknowledged (from a network
point of view) by the secondary node. When using protocol A,
it might be necessary to increase the size of this data
structure in order to increase asynchronicity between primary
and secondary nodes. But keep in mind that more asynchronicity
is synonymous with more data loss in the case of a primary
node failure. Since 8.0.13 resp. 8.2.7 setting the size
value to 0 means that the kernel should autotune this.
The default size is
128 KB, the default unit is KB.
-k,
--ko-count count In case the secondary node fails to complete a single write
request for count times the
timeout, it is expelled from the
cluster. (I.e. the primary node goes into StandAlone mode.)
The default is 0, which disables this feature.
-e, --max-epoch-size
val With this option the maximal number of write requests between
two barriers is limited. Should be set to the same as
--max-buffers . Values smaller than 100 can
lead to degraded performance. The default value is 2048.
-b,
--max-buffers val With this option the maximal number of buffer pages allocated
by DRBD's receiver thread is limited. Should be set to the
same as --max-epoch-size . Small values
could lead to degraded performance. (Minimum 32) The default value is
2048.
-u,
--unplug-watermark valWhen the number of pending write requests on the standby (secondary) node exceeds the unplug-watermark, we trigger the request processing of our backing storage device. Some storage controllers deliver better performance with small values, others deliver best performance when the value is set to the same value as max-buffers. Minimum 16, default 128, maximum 131072.
-m,
--allow-two-primaries With this option set you may assign primary role to both nodes. You only should use this option if you use a shared storage file system on top of DRBD. At the time of writing the only ones are: OCFS2 and GFS. If you use this option with any other file system, you are going to crash your nodes and to corrupt your data!
-a,
--cram-hmac-alg algYou need to specify the HMAC algorithm to enable peer authentication at all. You are strongly encouraged to use peer authentication. The HMAC algorithm will be used for the challenge response authentication of the peer. You may specify any digest algorithm that is named in /proc/crypto.
-x,
--shared-secret secretThe shared secret used in peer authentication. May be up to 64 characters.
-A,
--after-sb-0pri asb-0p-policypossible policies are:
disconnect
No automatic resynchronization, simply disconnect.
discard-younger-primary
Auto sync from the node that was primary before the split-brain situation occurred.
discard-older-primary
Auto sync from the node that became primary as second during the split-brain situation.
discard-zero-changes
In case one node did not write anything since the split brain became evident, sync from the node that wrote something to the node that did not write anything. In case none wrote anything this policy uses a random decision to perform a "resync" of 0 blocks. In case both have written something this policy disconnects the nodes.
discard-least-changes
Auto sync from the node that touched more blocks during the split brain situation.
discard-node-NODENAME
Auto sync to the named node.
-B,
--after-sb-1pri asb-1p-policypossible policies are:
disconnect
No automatic resynchronization, simply disconnect.
consensus
Discard the version of the secondary if the outcome
of the after-sb-0pri algorithm would also
destroy the current secondary's data. Otherwise disconnect.
discard-secondary
Discard the secondary's version.
call-pri-lost-after-sb
Always honor the outcome of the after-sb-0pri
algorithm. In case it decides the current
secondary has the right data, call the
pri-lost-after-sb on the current primary.
violently-as0p
Always honor the outcome of the after-sb-0pri
algorithm. In case it decides the current
secondary has the right data, accept a possible instantaneous
change of the primary's data.
-C,
--after-sb-2pri asb-2p-policypossible policies are:
disconnect
No automatic resynchronization, simply disconnect.
call-pri-lost-after-sb
Always honor the outcome of the after-sb-0pri
algorithm. In case it decides the current
secondary has the right data, call the
pri-lost-after-sb on the current primary.
violently-as0p
Always honor the outcome of the after-sb-0pri
algorithm. In case it decides the current
secondary has the right data, accept a possible instantaneous
change of the primary's data.
-P,
--always-asbpNormally the automatic after-split-brain policies are only used if current states of the UUIDs do not indicate the presence of a third node.
With this option you request that the automatic after-split-brain policies are used as long as the data sets of the nodes are somehow related. This might cause a full sync, if the UUIDs indicate the presence of a third node. (Or double faults have led to strange UUID sets.)
-R,
--rr-conflict role-resync-conflict-policy This option sets DRBD's behavior when DRBD deduces from its
meta data that a resynchronization is needed, and the SyncTarget
node is already primary. The possible settings are:
disconnect,
call-pri-lost and
violently. While disconnect
speaks for itself, with the call-pri-lost
setting the pri-lost handler is called
which is expected to either change the role of the node to
secondary, or remove the node from the cluster.
The default is disconnect.
With the violently setting you allow DRBD
to force a primary node into SyncTarget state. This means
that with that action the data exposed by DRBD change to
the SyncSource's version of the data instantaneously.
USE THIS OPTION ONLY IF YOU KNOW WHAT YOU ARE DOING.
-d,
--data-integrity-alg hash_alg DRBD can ensure the data integrity of the user's data on the network
by comparing hash values. Normally this is ensured by the 16 bit checksums
in the headers of TCP/IP packets. This option
can be set to any of the kernel's data digest algorithms.
In a typical kernel configuration you should have
at least one of md5, sha1, and crc32c
available. By default this is not enabled.
See also the notes on data integrity on the drbd.conf manpage.
-o,
--no-tcp-cork DRBD usually uses the TCP socket option TCP_CORK to hint to the network stack when it can expect more data, and when it should flush out what it has in its send queue. It turned out that there is at lease one network stack that performs worse when one uses this hinting method. Therefore we introducted this option, which disable the setting and clearing of the TCP_CORK socket option by DRBD.
-p,
--ping-timeout ping_timeoutThe time the peer has to answer to a keep-alive packet. In case the peer's reply is not received within this time period, it is considered as dead. The default value is 500ms, the default unit is 100ms.
-D,
--discard-my-data Use this option to manually recover from a split-brain situation. In case you do not have any automatic after-split-brain policies selected, the nodes refuse to connect. By passing this option you make a node to sync target immediately after successful connect.
Changes the synchronization daemon parameters of
device at runtime.
-r,
--rate rateTo ensure smooth operation of the application on top of DRBD, it is possible to limit the bandwidth that may be used by background synchronization. The default is 250 KB/sec, the default unit is KB/sec.
-a,
--after minor Start resync on this device only if the device with
minor is already in connected
state. Otherwise this device waits in SyncPause state.
-e,
--al-extents extents DRBD automatically performs hot area detection. With this
parameter you control how big the hot area (=active set) can
get. Each extent marks 4M of the backing storage. In case a
primary node leaves the cluster unexpectedly, the areas covered
by the active set must be resynced upon rejoining of the failed
node. The data structure is stored in the meta-data area,
therefore each change of the active set is a write operation
to the meta-data device. A higher number of extents gives
longer resync times but less updates to the meta-data. The
default number of extents is
127. (Minimum: 7, Maximum: 3843)
-v,
--verify-alg hash-alg During online verification (as initiated by the
verify sub-command),
rather than doing a bit-wise comparison, DRBD applies a hash function
to the contents of every block being verified, and compares that
hash with the peer. This option defines the hash algorithm being
used for that purpose. It can be set to any of the kernel's data
digest algorithms. In a typical kernel configuration you should have
at least one of md5, sha1, and crc32c
available. By default this is not enabled; you must set this
option explicitly in order to be able to use on-line device verification.
See also the notes on data integrity on the drbd.conf manpage.
-c,
--cpu-mask cpu-mask Sets the cpu-affinity-mask for DRBD's kernel threads of this
device. The default value of cpu-mask is
0, which means that DRBD's kernel threads should be spread over
all CPUs of the machine. This value must be given in hexadecimal
notation. If it is too big it will be truncated.
Sets the device into primary role. This
means that applications (e.g. a file system) may open the
device for read and write access. Data
written to the device in primary role are
mirrored to the device in secondary role.
Normally it is not possible to set both devices of a connected DRBD device
pair to primary role. By using the --allow-two-primaries
option, you override this behavior and instruct DRBD to allow two
primaries.
-o,
--overwrite-data-of-peerBecoming primary fails if the local replica is inconsistent. By using this option you can force it into primary state anyway. USE THIS OPTION ONLY IF YOU KNOW WHAT YOU ARE DOING.
Sets the device into secondary state.
This operation fails as long as at least one application (or file
system) has the device open for write access.
It is however, possible that both devices of a connected DRBD device pair are in secondary state.
This initiates on-line device verification. During on-line verification,
the contents of every block on the local node are compared to those on
the peer node. Device verification progress can be monitored via
/proc/drbd.
Any blocks whose content differs from that of the corresponding block
on the peer node will be marked out-of-sync in DRBD's on-disk bitmap; they
are not brought back in sync automatically. To
do that, simply disconnect and reconnect the resource.
This command will fail if the device is
not part of a connected device pair.
See also the notes on data integrity on the drbd.conf manpage.
This forces the local device of a pair of connected DRBD devices into SyncTarget state, which means that all data blocks of the device are copied over from the peer.
This command will fail if the device is
not part of a connected device pair.
This forces the local device of a pair of connected DRBD devices into SyncSource state, which means that all data blocks of the device are copied to the peer.
Returns as soon as the device can
communicate with its partner device.
-t,
--wfc-timeout wfc_timeout, -d,
--degr-wfc-timeout degr_wfc_timeout, -w, --wait-after-sb This command will fail if the
device cannot communicate with its
partner for timeout
seconds. If the peer was working before this node was
rebooted, the wfc_timeout is used. If the peer was already
down before this node was rebooted, the degr_wfc_timeout
is used.
The default value for wfc_timeout
is 0 which means to wait forever. The default for
degr_wfc_timeout is 120 seconds.
In case the connection status goes down to StandAlone because
the peer appeared but the devices had a split brain situation,
the default for the command is to terminate. You can change this
behavior with the --wait-after-sb option.
Returns as soon as the device leaves any
synchronization into connected state. The options
are the same as with the wait-connect
command.
Removes the information set by the net command
from the device. This means
that the device goes into unconnected
state and will no longer listen for incoming connections.
Removes the information set by the disk command
from the device. This means
that the device is detached from its
backing storage device.
Removes all configuration information from the
device and forces it back to
unconfigured state.
Shows the current status of the device in xml-like format. Example output:
<resource minor="0" name="s0" cs="SyncTarget" st1="Secondary" st2="Secondary"
ds1="Inconsistent" ds2="UpToDate" resynced_precent="5.9" />
This causes DRBD to reexamine the size of the
device's backing storage device. To
actually do online growing you need to extend the backing storages
on both devices and call the resize command one of
your nodes.
Temporarily suspend an ongoing resynchronization by setting the local pause flag. Resync only progresses if neither the local nor the remote pause flag is set. It might be desirable to postpone DRBD's resynchronization after eventual resynchronization of the backing storage's RAID setup.
Mark the data on the local backing storage as outdated. An outdated
device refuses to become primary. This is used in conjunction with
fencing and by the peer's outdate-peer handler.
If the outdate-peer handler fails to stonith the peer node,
and your fencing policy is set to
resource-and-stonith, you can unfreeze IO operations with this
command.
Displays every state change of DRBD and all calls to helper programs. This might be used to get notified of DRBD's state changes by piping the output to another program.
-a,
--all-devicesDisplay the events of all DRBD minors.
-u,
--unfilteredThis is a debugging aid that displays the content of all received netlink messages.
Generates a new currend UUID and rotates all other UUID values. This works on disconnected devices only, the device might be in primary or secondary role. Available option:
-c,
--clear-bitmapClears the sync bitmap in addition to generating a new current UUID.
This can be used to shorten the initial resync of a cluster where the second node is added after the first node is gone into production, by means of disk shipping. The necessary steps are:
device new-current-uuid --clear-bitmapdevice new-current-uuid
Written by Philipp Reisner <philipp.reisner@linbit.com>
and Lars Ellenberg <lars.ellenberg@linbit.com>